The present invention relates to intraocular lens combinations. More particularly, the invention relates to intraocular lens combinations which are adapted to provide substantial benefits, such as accommodating movement and/or inhibition of posterior capsule opacification (PCO) in the eye.
The human eye includes an anterior chamber between the cornea and iris, a posterior chamber, including by a capsular bag, containing a crystalline lens, a ciliary muscle, a vitreous chamber behind the lens containing the vitreous humor, and a retina at the rear of this chamber. The human eye has a natural accommodation ability. The contraction and relaxation of the ciliary muscle provides the eye with near, intermediate and distant vision. This ciliary muscle action shapes the natural crystalline lens to the appropriate optical configuration for focusing light rays entering the eye on the retina.
After the natural crystalline lens is removed, for example, because of cataract or other condition, a conventional, monofocal IOL can be placed in the posterior chamber. Such a conventional IOL has very limited, if any, accommodating ability. However, the wearer of such an IOL continues to require the ability to view both near and far (distant) objects. Corrective spectacles may be employed as a useful solution. Recently, multifocal IOLs without accommodating movement have been used to provide near/far vision correction.
Attempts have been made to provide IOLs with accommodating movement along the optical axis of the eye as an alternative to shape changing. Examples of such attempts are set forth in Levy U.S. Pat. No. 4,409,691 and several patents to Cumming, including U.S. Pat. Nos. 5,674,282 and 5,496,366. The disclosure of each of these patents is incorporated herein by reference.
One problem that exists with such IOLs is that they often cannot move sufficiently to obtain the desired accommodation. The degree of accommodation has been closely related to the lens prescription of the individual patient. In addition, the presence of such lenses can result in cell growth from the capsular bag onto the optics of such lenses. Such cell growth, often referred to as posterior capsule opacification (PCO), can interfere with the clarity of the optic to the detriment of the lens wearer""s vision.
It would be advantageous to provide IOLs adapted for accommodating movement, which can preferably achieve an acceptable amount of accommodation and/or a reduced risk of
New intraocular lens combinations (ILCs) have been disclosed. The present ILCs provide distance, near and intermediate vision through position, preferably axial position, changes in the eye. The present combinations preferably enhance the degree of accommodation achieved in spite of the movement and space limitations within the eye. One advantage of the present ILCs is the ability to standardize the prescription or optical power of the moving or accommodating lens of the ILC. Thus, the required amount of movement in the eye to achieve accommodation can be substantially the same for all patients. This greatly facilitates the design of the moving or accommodating lens. Further, with at least certain of the present ILCs, inhibition of PCO is obtained. The present ILCs are relatively straightforward in construction, can be implanted or inserted into the eye using systems and procedures which are well known in the art and function effectively with little or no additional treatments or medications being required.
In one broad aspect of the present invention, intraocular lens combinations (ILCs) comprise a first optic, second optic and a movement assembly. The first optic has a negative optical power and is adapted to be placed in a substantially fixed position in a mammalian eye. The second optic has a higher optical power than the first optic. The movement assembly is coupled to the second optic and is adapted to cooperate with the eye, for example, the zonules, ciliary muscle and capsular bag of the eye, to effect accommodating movement of the second optic in the eye.
Advantageously, the second optic has a high plus optical power to reduce the amount of movement, for example, axial movement, in the eye needed to provide accommodation for intermediate and near vision. The negative or minus optical power of the first optic compensates for the excess plus or positive optical power in the first optic. The use of such a compensating lens, that is the first optic having a negative optical power, can allow, for standardization of the optical power correction in the second optic. In other words, the optical power of the second optic, that is the movable optic, can be approximately equal from optic to optic, while the optical power of the first optic, that is the fixed optic, is adjusted from optic to optic to meet the specific vision correction needs (prescription) of each individual patient. Consequently, the required amount of movement of the second optic in the eye can be approximately the same for all patients.
The present ILCs provide accommodation, preferably an acceptable degree of accommodation, in spite of movement and space limitations in the eye. For example, the maximum theoretical amount of axial movement for a simple disc lens having an overall diameter of 11 millimeters (mm) and an optic diameter of 5 mm that undergoes 1 mm of compression in its diameter is about 1.65 mm. The amount of axial movement required for a plus 15 diopter optic to provide 2.5 diopters of additional power in the spectacle plane is about 2.6 mm. However, a plus 30 diopter optic requires only 1.2 mm of axial movement to provide 2.5 diopters of additional power in the spectacle plane. Thus, by increasing the plus power of the second optic, which is adapted for accommodating movement, a reduced amount of movement is needed to achieve higher or enhanced degrees of accommodation. The first or fixed optic preferably has a minus power to compensate for the excess plus power in the second optic.
The present ILCs preferably include first and second optics with optical powers which provide a net plus optical power. To illustrate, assume that the patient requires a plus 15 diopter correction. The first optic is provided with a minus 15 diopter optical power and the second optic with a plus 30 diopter optical power. The net optical power of this ILC is approximately the sum of minus 15 diopters and plus 30 diopters or plus 15 diopters, the desired prescription for the patient in question. The powers of the first and second optics are only approximately additive since the net power of the combination also depends on other factors including, but not limited to, the separation of the two optics, the magnitude of the power of each individual optic and its location in the eye and the like factors. Also, by adjusting the optical power of the first optic, the net optical power of the ILC can be adjusted or controlled even though the optical power of the second optic is standardized or remains the same, for example, at a plus 30 diopter optical power. By standardizing the optical power of the second optic, the amount of movement in the eye required to obtain a given level of accommodation is substantially the same, and preferably well within the space limitations in the eye, from patient to patient.
In one very useful embodiment, the movement assembly comprises a member including a proximal end region coupled to the second optic and a distal end region extending away from the second optic and adapted to contact a capsular bag of the eye. Such movement assembly may completely circumscribe the second optic or may be such as to only partially circumscribe the second optic.
The second optic preferably is adapted to be positioned in the capsular bag of the eye.
The first optic may be coupled to a fixation member, or a plurality of fixation members, adapted to assist in fixating the first optic in the eye. Each fixation member preferably has a distal end portion extending away from the first optic. In one embodiment, the distal end portion of the fixation member is adapted to be located in the capsular bag of the eye. Alternately, the distal end portion of the fixation member may be located in contact with a sulcus of the eye. As a further alternate, the distal end portion of the fixation member may be adapted to be located in an anterior chamber of the eye.
The first optic may be located posterior in the eye relative to the second optic or anterior in the eye relative to the second optic. In a useful embodiment, the first optic is adapted to be positioned in contact with the posterior wall of the capsular bag of the eye. This positioning of the first optic provides for effective compensation of the plus or positive vision correction power of the second optic. In addition, by having the first optic in contact with the posterior wall of the capsular bag, cell growth from the capsular bag onto the ILC, and in particular onto the first and second optics of the ILC, is reduced. This, in turn, reduces the risk of or inhibits posterior capsule opacification (PCO).
In one embodiment, the fixation member or members and the movement assembly are secured together, preferably permanently secured together. Thus, when inserting the ILC into the eye, a single combined structure can be inserted. This reduces the need to position the first and second optics relative to each other. Put another way, this feature allows the surgeon to very effectively and conveniently position the ILC in the eye with reduced surgical trauma to the patient.
The fixation member and movement assembly may be secured, for example, fused, together at the distal end portion of the fixation member and the distal end region of the movement assembly.
In another broad aspect of the present invention, ILCs are provided which comprise a first optic having a posterior surface adapted to be positioned in contact with a posterior wall of the capsular bag of the eye; a second optic adapted to focus light toward a retina of the eye; and a movement assembly coupled to the second optic and adapted to cooperate with the eye to effect accommodating movement of the second optic in the eye. The first optic has a substantially plano optical power or a negative optical power. These ILCs are particularly adapted to inhibit PCO.
The first optic of these combinations preferably is adapted to be placed in a substantially fixed position in the eye. The posterior surface of the first optic advantageously is configured to substantially conform to a major portion, that is, at least about 50%, of the posterior wall of the capsular bag of the eye in which the combination is placed. More preferably, the posterior surface of the first optic is configured to substantially conform to substantially all of the posterior wall of the capsular bag. Such configuration of the first optic is very useful in inhibiting cell growth from the eye onto the first and second optics and in inhibiting PCO.
In one embodiment, the first optic has a substantially plano optical power and the second optic has a far vision correction power. In an alternate embodiment, the first optic has a negative optical power and the second optic has a positive optical power, more preferably, so that the optical powers of the first and second optics provide a net plus optical power in the eye in which the combination is placed.
In a very useful embodiment, the first optic includes an anterior surface and at least one projection extending anteriorly from this anterior surface. The at least one projection is positioned to limit the posterior movement of the second optic in the eye. Thus, the movement of the second optic is effectively controlled to substantially maintain the configuration of the combination and/or to substantially maintain an advantageous spacing between the first and second optics.
The movement assembly may be structured and functions similarly to movement assembly of the previously described ILCs.
The first optic may have a fixation member or members coupled thereto. The fixation member or members are adapted to assist in fixating the first optic in the eye, that is in contact with the posterior wall of the capsular bag of the eye. In one embodiment, the first optic itself is configured and/or structured so that no fixation member or members are needed to maintain the first optic in contact with the posterior wall of the capsular bag of the eye. The first optic and the movement assembly of these ILCs may be secured together.
In general, the first and second optics of the present ILCs may be made of any suitable materials. Preferably, the first and second optics are made of polymeric materials. More preferably, the first and second optics and the movement assembly, and the fixation member(s), if any, are deformable for insertion through a small incision in the eye.
The present movement assemblies are sufficiently flexible to facilitate movement of the second optic in the eye upon being acted upon by the eye. In one very useful embodiment, the movement assembly includes a hinge assembly, preferably adapted and positioned to facilitate the accommodating movement of the second optic.
In those embodiments in which the first optic has a substantially plano optic power, the second optic preferably has a far vision correction power, more preferably such a power for infinity, in the unaccommodated state.
In a further broad aspect of the present invention, methods for inserting an ILC in an eye are provided. Such methods comprise providing an ILC in accordance with the present invention, as described herein. The ILC is placed into the eye, for example, in the capsular bag of the eye or partly in the capsular bag of the eye, using equipment and techniques which are conventional and well known in the art. The ILC is placed in a rest position in the eye, for example, a position so that the eye, and in particular the ciliary muscle and zonules of the eye, effectively cooperate with the movement assembly to move the second optic of the ILC anteriorly in the eye from the rest position to provide for positive accommodation. No treatments or medications, for example, to paralyze the ciliary muscle, to facilitate fibrosis or otherwise influence the position of the ILC in the eye, are required.
Preferably, the first and second optics and the movement assembly are deformed prior to being placed into the eye. Once the ILC is placed in the eye, and after a normal period of recovery from the surgical procedure, the ILC, in combination with the eye, provides the mammal or human wearing the ILC with effective accommodation, preferably with reduced risk of PCO. In the unaccommodated state, the ILC preferably provides the mammal or human wearing the ILC with far vision correction.
Any and all features described herein and combinations of such features are included within the scope of the present invention provided that the features of any such combination are not mutually inconsistent.